The urogenital area harbors a complex microbial ecosystem comprising more than 50 different bacterial species (Hill et al., Scand. J. Urol. Nephrol. 1984; 86 (suppl.) 23-29). The dominating species in this area for fertile women are lactic acid producing bacteria belonging to the genus Lactobacillus. These lactic acid producing members are important for retaining a healthy microbial flora in these areas, and act as probiotic bacteria with an antagonistic effect against pathogenic microbial species. Lactic acid producing bacteria inhibit growth and colonization by other microorganisms by occupying suitable niches for colonization, by forming biofilms and competing for available nutrients, thereby excluding colonization by harmful microorganisms. Also, the production of hydrogen peroxide, specific inhibiting substances, such as bacteriocines, and organic acids (including lactic acid and acetic acid) that lower the pH, inhibit colonization by other microorganisms.
The microbial ecosystem of a healthy individual can be disturbed by the use of antibiotics, during hormonal changes, such as during pregnancy or use of contraceptives with estrogen, during menstruation, after menopause, in people suffering from diabetes etc. Also, microorganisms may spread from the anus to the urogenital area, thereby causing infections. This results in a disturbance of the normal microbial flora and leaves the individual susceptible to microbial infections that cause vaginitis, urinary tract infections and ordinary skin infections. Microorganisms commonly associated with these kinds of infections belong to the genera ° E. scherichia, Enterococcus, Psedomonas, Proteus, Klebsiella, Streptococcus, Staphylococcus, Gardnerella and Candida. Women are at particular risk due to their shorter distance between the anus and the urogenital tract; especially at risk are young women, who not yet have a well developed microflora in the urogenital area and older women, who no longer have a protective flora.
One way to reduce the problems with the kinds of infections described above is to have a good personal hygiene. However, excessive use of cleaning agents not only decreases the amount of harmful microbes, but can harm the beneficial microbial flora, again render it susceptible for pathogenic species to colonize and cause infections.
Alternatively, administration of lactic acid producing bacteria to the urogenital area and the skin in order to outcompete pathogenic species and facilitate reestablishment and maintenance of a beneficial microbial flora in these areas, have been found to be a successful means to treat and prevent microbial infections.
It has been suggested that lactic acid producing bacteria can be delivered via absorbent products, such as diapers, sanitary napkin, incontinence guards, panty liners and tampons, as described in, for example, WO 92/13577, WO 97/02846, WO 99/17813, WO 99/45099 and WO 00/35502.
A major problem with providing products intended to be used for transfer of lactic acid producing bacteria, is that the bacteria have to retain viability during transport and storage of the products. Lactic acid producing bacteria rapidly loose viability under semi-moist conditions, and it is therefore important that the bacteria are not uncontrollably exposed to moisture. With “semi-moist” conditions is meant that the water activity (aw) is between about 0.2 and about 0.9. One way to partly overcome this problem in absorbent products provided with lactic acid producing bacteria has been to supply the products with the bacteria, drying said products to remove most of the moisture and enclosing the products in moisture impervious packages (WO 99/17813; EP B1 1 210 277). However, since the entire absorbent product is packed together with the moisture sensitive bacteria, it is necessary, as stated above to dry said absorbent product to a high extent.
This is in conventional processes for producing absorbent articles very difficult to achieve. This is also an inflexible solution since once the product has been dried it is necessary to enclose it quickly in the moisture impervious package before moisture starts to act on the lactic acid producing bacteria. Further since these moisture impervious packages are produced from expensive films these kinds of large packages are quite costly.
An alternative way to protect bacteria against moisture has been to disperse the bacteria in a hydrophobic substance (see e.g. U.S. Pat. No. 4,518,696; WO 92/13577; WO 02/28446) which due to its hydrophobic character will prevent moisture to reach the embedded bacterial cells. The problem with this is that when folding and packaging the product the hydrophobic substance wherein the bacteria is dispersed sticks to the package or smears over the product in an undesired manner which makes the product look messy. If the hydrophobic substance is smeared over the topsheet this may also have a negative impact on the absorbance due to clogging of the pores in the topsheet. The desired effect may also be reduced since some of the bacteria disappears with the package when removing the package or alternatively ends up on a location on the product where it does not come in direct contact with the urogenital area upon usage.